A number of studies have demonstrated the effects of selective P2X3 antagonist treatment. These include blockade of ATP-evoked currents in mouse and rat [27] dorsal root ganglia neurones, as well as reduction of chemical-induced pain [24], inflammatory pain [27], and neuropathic pain [27] in rat. Hyporeflexia in the rat urinary bladder in response to antagonist treatment has also been demonstrated [17].